In recent years, a composite material having both strength of metal and light-weight and formability of plastic has been developed. Examples of the composite material may include fiber reinforced plastic (FRP) and carbon fiber reinforced plastic (CFRP).
Such a composite material is a frontier composite material that has been noticed as a light-weight structural material of high strength and high elasticity and uses fiber (carbon fiber) as a reinforcing material, and has an excellent characteristic as the light-weight structural material. Due to the characteristic of the composite material, more products have been manufactured by using a mixture of the composite material and a metal material, and in order to manufacture such products, a method for strongly adhering the metal material and the composite material is important.
Technologies for processing the composite material and forming the products have been actively used, but a method for adhering different kinds of materials such as the composite material and the metal material has been recently developed. As a representative method for adhering different kinds of materials such as the composite material and the metal material, a method for mechanically adhering the composite material and the metal material by using a general rivet, a self-piercing rivet, and a bolt.
However, as compared to a welding method, such an adhering method may have demerits in that manufacturing cost is increased, an appearance quality of an adhering article is degraded, investment cost is increased due to a change of an adhering facility and manufacturing environment caused by changing adhering materials, and a structure of the adhering facility is complicated.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the disclosure, and therefore, it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.